The present invention relates to an information processing system to execute online processing and batch processing, and in particular, to a method of recovering data stored on a storage media such as a storage, for example, a disk destroyed by a failure or the like of online processing and/or batch processing.
In online processing and batch processing executed in an information processing system of a bank, a securities company, or the like, when the processing is abnormally terminated by a bug of a program, a failure of a storage, or the like, integrity of data may be lost depending on cases. Important data may be destroyed or erased by a mistake made by a human working in the information processing system.
There have been known several techniques which restore the information processing system in such a failed state and which solve conflict of data integrity to restart the processing interrupted or to execute again the processing interrupted. One of such recovery technique uses “backup and restoration”.
In the recovery of “backup and restoration”, for example, when the recovery is applied to a database system, a backup of data is periodically stored on a recording media such as a magnetic tape. At occurrence of a failure in the system, the backup on the magnetic tape is restored in the storage to recover the data of the storage up to an appropriate point using a log file. The database data is resultantly recovered to an appropriate state and the database processing can be restarted.
In batch processing system, data is stored as backup data on a magnetic tape before batch processing is started. When the processing is thereafter abnormally terminated, the backup data is read from the magnetic tape to restore data of the storage to a state before the start of batch processing. The batch processing is then re-executed beginning at its start point.
When data is restored in the recovery of “backup and restoration” of the prior art, data in the areas on the magnetic tape not updated from when the backup data is stored (data in the areas whose data matches that stored in the storage) is also read from the magnetic tape and is written in the storage. This data transfer is actually unnecessary and elongates the period of time required for the restoration (reference is to be made to FIG. 17A).
In a case in which areas A, B, and C are specified as a backup and restoration unit in the storage, when each area thereof is individually accessed and hence only area A is required to be recovered, the restoration is carried out for areas A to C. This also elongates the restoration time. During the data restoration, processing which uses data in areas A to C must be interrupted. This adversely influences efficiency of the overall processing (reference is to be made to FIG. 17B).